When manufacturing tires, particularly vehicle tires having internal body plies formed from nylon cords or other synthetic fibers which shrink when cooled, it is now customary to subject each tire, upon extraction from the curing mold, to a stabilizing operation generally consisting in mounting the tire on a support, inflating it to a given pressure, usually of about 3 atmospheres, and maintaining this pressure long enough for the tire to cool below a given temperature, usually of about 100.degree. C.
Such a process, usually referred to as "post inflation", provides, not only for preventing the synthetic cords from shrinking, thus avoiding undesired distortion of the tire, but also for stabilizing the shape of the cords, which is extremely useful in terms of finished tire quality. Stabilizing cured tires poses a number of problems for the manufacturer: relatively high-cost facilities; the energy required for cooling the tires; and the total loss of the heat given off by the tires during stabilization.
Moreover, those skilled in the art are familiar with the problems faced by vehicle tire manufacturers for obtaining as homogeneous an output as possible from each facility, combined with a high quality standard compatible with minimum production cost. As homogeneous output depends solely, and particularly at the curing stage, in varying a relatively large number of parameters for adapting them to various continually variable external parameters, compromise solutions must often be adopted for limiting production cost. For instance, as the ambient temperature of a facility, which is undoubtedly the most decisive external variable, may fluctuate over a fairly wide range, the number of calories supplied to the green tires during curing would need to be varied continually as a function of initial green tire temperature. As this would be unacceptable in terms of cost, manufacturers frequently opt to over- rather than undercuring of tires.
This and other similar problems could be solved by uniforming the initial conditions of the green tires, for instance, by preheating them to a given constant temperature prior to curing. The additional cost involved at present for implementing such a solution, however, would be such as to be economically unfeasible.